Automatic block-signaling system for railways



W. H. WORKMAN.

AUTOMATIC BLOCK SIGNALING SYSTEM FOR RAILWAYS. APPLICATION FILED AUG-26. T916.

Patented Nov. 3% W20.

2 SHEETS-SHEET I.

MAM/v A TTOR/l/EV W. H. WOHKMAN. AUTOMATIC BLOCK SIGNALING SYSTEM FOR RAIILWAYS.

APPLICATION FILED AUG-26; 1916.

2 SHEETS-SHEET 2.

,ATTOR'NEY,

Patented Nov 30, mm.

Km m m mz w UNITED STATES PATENT OFFICE.

WILLIAM H. WORKMAN, OF ROCHESTER, NEW YORK, ASSIGNOR TO GENERAL RAILWAY SIGNAL COMPANY, OF GATES, NEW YORK, A CORPORATION OF NEW YORK.

Specification of Letters latent.

Patented Nov. 30, 1920.

Application filed August 26, 1916. Serial No. 117,065.

T 0 all whom it may concern:

Be it known that I, WILLIAM H. WORK- MAN, a citizen of the United States, and a resident of the city of Rochester, in the county of Monroe and State of New York, haveinvented a new and useful Automatic Block-Signaling System for Railways, of which the following is a specification.

This invention relates to signaling sys tems for railways and more particularly to automatic block signaling systems in which polarized track circuits are used.

The principles and operation of thecommon automatic block signaling system for railways are too well known to those skilled in the art of railway signalingto require special description and explanation and the practice of using polarized track circuits to obtain the three indications used in such block signaling systems is also well known. Heretofore, however, to the best of my knowledge, it has been found impractical to apply the polarized track circuit control in its simplest form to block signaling systems in which the different indications or aspects oi the signals arecaused by the closing of circuits, as for instance, in systems using the well known light signals, as distinctive from those systems in which the indications or aspects of the signals are caused by the interruption of circuits, as for instance, in the case of the ordinary semaphore signal. The reason for this will be easily understood by those skilled in the art when it is recalled that according to established practice with polarized track circuit control, the stop indication is obtained when atrack relay is deenergized, the proceed indication when the track relay is energized by current of one polarity, and the caution indication when the track relay is energized by current of the other polarity; and it can be seen that when these indications are given by the closing of circuits, as is the case in systems using light signals, the common and frequently occurring change from a cautionindication to a proceed indication results in the giving of a stop indication temporarily while the track relay is changing from its condition oi being energized by current of one polarity to its condition of being energized by current of the opposite polarity. in other words, a track relay suitable for use with polarized track circuit control in automatic block signaling systems in which the indications are given by the closing of circuits, generally operates a three position circuit controlling device, having two extreme positions corresponding to the respective energized conditions of the relay and an intermediate position corresponding to the deenergized condition of the relay; and when the relay changes from either one of its energized conditions to its other energized condition, the circuit giving the stop indication is temporarily closed in the intermediate position of the circuit controlling de vice operated by the relay, since it is apparent that, in order to change such a circuit controlling device from either ofiits extreme positions to its other extreme position, it is necessary to pass through the intermediateposition. Suppose that the polarized track circuit control is applied to a system using such track relays operating a three position circuit controlling device of the type above mentioned, and suppose that the track relays directly control light signals, then it can be seen that every change from a caution indication to :1 proceed indication, or vice verse, is accompanied by the brief occurrence of the stop indication, which is highly objectionable, because a train approaching a signal having a caution aspect and expecting this signal to change to the proceed aspect is falsely given a stop indication when this change takes place, and although this improper stop indication is only temporary, it is very disconcerting to the engineer or motor-man and causes either unnecessary attempts to stop or failures to attempt to stop when such attempts should be made.

-With these considerations in mind, one of the principal objects of this invention. is to devise a simple and practical automatic block signaling system for railways in which polarised track circuit control may he used in connection with signals which give their indications by the closing of circuits,

A further object of the invention is to de rise a simpie and practical automatic blocli: signaling system for railways in whicl 1 possible to obtain three indications by signals controlled direct it relays without obtaining}: aspects.

H ther objects and admin agile as the description of the invention progresses, and the novel features of the invention will be particularly pointed out in the ap ended claims.

n describing the invention in detail reference is had to the accompanying drawings, wherein I have illustrated a preferred physical embodiment of my invention, and wherein like characters of reference designate corresponding parts throughout the several views, and-in which? Figure 1 is a diagrammatic view which shows a stretch of track, together with an arrangement of light signals suitable for controlling trafiicin one direction over this stretch of track, and which illustrates a preferred form of construction and arrangement of parts and circuits embodying this invention; and

- Fig. 2is a perspective diagrammatic view of the track rela used-in the signaling sys-' tem shown ii Fig. 1, the contact fingers of said relay being in the intermediate or biased position. 1

Referring to Fig. 1 of the drawings, the track rails 1 and 2 extend throughout the length of the trackway and are divided at intervals by insulatin joints 3 into track sections or blocks, as i, B, C, and D. The normal direction of traffic over this stretch of track is from left to right, as indicated by the arrow a; and at the entrance end of each of the blocks is located a signal, herein shown as a light signal, which may be of any suitable or well known type, these signals bein designated 4, 5, and 6 for the blocks B, and'D, respectively. Electrical energy for the system may be derived from any suitable source, but is shown as supplied from line wires 8 and 9 which extend throughout the length of the track, and

which are connected at one end to an alternating current generator 10. Connected across the line wires 8 and 9 are the primaries of transformers 11, 12 and 13 which are associated with the blocks A, B, and C. respectively. Also associated with the blocks B, C, and D are alternating current track relays of the type commonly known as polyphase or two element relays, said relays betimes energized. Since the relays 15 and 16 for the blocks C and D, respectively, have the same windings and are constructed and connected in the same manner as the relay 14 for the block B, the corresponding parts of these relays are for simplicity given the same reference numerals with distinctive exponents added; and a brief description of one of these relays will suflice for all.

The relay 14, as shown in Fig. 1, has four groups of contact fingers, two of which are of the ordinary and well known type commonly used in relays in the railway signaling art, and are adapted to close a circuit in either of two extreme positions; and the other two groups of which are so constructed and arranged as to close a circuit in the intermediate or deenergized position of the relay and to open this circuit in either of its extreme positions and to keep this circuit open while the relay is operated continuously from either one of its extreme positions, through said intermediate position, to the other of said extreme positions.

One form of a construction of a track relay capable of performing the functions necessary to make it applicable to the system embodying this invention is shown in Fig. 2; and in this construction the motor for operating the relay, being of the well known type, is shown diagrammatically. This motor may be rotated in one direction or the other depending upon the phase relation of the currents in its local and track windings 20 and 17. and is connected to a pinion 26. Meshing with thepinion 26 is a toothed sector 27 which is fastened to a block 28 supported on a shaft 29, the ends of which are cone-shaped and are inserted in any suitable fixed bearings (not shown) so that the sector 27 and the shaft 29 may oscillate. Upon the shaft 29 are loosely supported weighted arms 30 and 31, the weighted ends of which are adapted to rest normally on a fixed base plate 32. As the sector 27 is rocked with the shaft 29 in the direction indicated bythe arrow 6, due to the rotation of the pinion 26, the arm 30 will be lifted by the block 28 and will remain in its lifted position as long as a turning torque is exerted on the pinion 26; but when the turning torque on the pinion 26. ceases to be exerted. the weight of the arm 30 will return the sector 27 and the block 28 to their intermediate position. The same action occurs when the sector 27 is rocked in a direction opposite to the direction indicated by the arrow 1). except that in this case the sector 27 will be returned to its intermediate position by the arm 31. In other words, the sector 27 is biased in its intermediate position.

Connected to the block 28 by the arm 33 and the link 34, and adapted to be rocked by the movement of said block 28, is a contact carrying block 35 which is pivoted at each end by means of pivot pins 36, only one of these pins 36 being shown, these pivot pins 36 being journaled in supports 37, a fragment of one support 37 being shown.

The contact carrying block 35 which is made of suitable insulating material carries a number of contact fingers 7072, 88, 95 and 82-84; but since the way in which these contact fingers are connected to said block 35 has been fully shown and described in the Patent #1,012,08l granted to W. K. Howe; December19, 1911, a bricf'description of the way of supportin said fin ers on said block is considered 'su cient. ach of these contact fingers is pressed tightly by 'a spring 46 against a bearing strip 45 which is fixed to the block 35 andwhich has its end portions bent up and formed with notches; and the corresponding contact finger is similarly bent and bears against the bottom edges of said notches, so that relative movementof a contact finger and said block 35 is permitted by compressing the spring 46. The contact fingers are arranged to cooperate with suitable fixed contact posts (SQ-73, 89-98, 94, 8185 which are supported in any convenient manner, as for instance in the relay casing not shown) and the engagement of these contact fingers with said osts at different times controls certain circuits.

Each of the contactfingers 88 and 95 is of the well known type commonly used in relays, and has resilient members adapted to make contact with front and back contacts in the usual way. The two pairs of fingers I 7 0-7 2 and'80--84 are constructed. the same; and the fin ers of each pair are mounted on opposite of the block 35 and are arranged to engage their respective contact posts when said block is in its ,biased or neutral position. These fingers of each pair 'are connected by-flexible conductors 71 and 83, so that when these fingers are spread apart into contact with their respective contact posts, a circuit is completed between said posts. I a

An inertia member 47 having weighted ends 47 and 47 is pivotally supportedon an arm 48, which is fixed to the block 35 by means of screws 49, and said inertia memher is also connected to the contact fingers Z0 -72, by means of links 50 and 51, which are pivotally connected at their ends to said contact fingers and to said inertia member.

. Stops 52 and 53 are fixed to said arm 48=to limit the movement of said inertia member 47 about its axis in eitherdirection.

The parts of the relay are shown in Fig. 2 in the position corresponding to the deener ized condition of the relay. The fingers 2 are spread apart and establish a circuitwhich, in the arrangement illustrated, lights a red lamp B. When the relay is energized, pinion 26 is rotated in one direc-' tion or the other.

When the pinion 26 is rotated; in the direction indicated by the arrow 0, the sector 27 and block 28 will also be rocked in the directact finger 72 is held substantially station-- ary by the contact post 73, while the contact finger 70 is moved downward away from the contact post 69 with the block 35. And at the same time the inertia member 47 is rocked about its axis until its upper end strikes the stop 52 by reason of the fact that the contact finger 72 is held substantially stationa while-the arm. 48 and the pin on which theinertia member 47 is pivoted is moved downward, so that the link 51 causes said inertia member to turn. In this way the circuit for lighting the red lamp R, closed between contacts 69 -7 3, is interrupted. Also, when the contact carrying block 35 is rocked clockwise as above described the contact finger 88 is moved down into contact with its post 94, thereby estab- 'lishing a circuit, which in the arrangement shown lights a yellow lamp Y.

In this way by energizing the motor of the relay so as to cause the pinion 26 to be rotated in the. direction indicated by the arrow 0, the stop indication is changed to a caution indication. Upon subsequent-deener- 'gization of the motor of the relay, the parts are restored to the biased position and the caution indication Ygiven by the lighting of the yellow lamp is changed back to the stop indication given by llghtingthe red lamp R, due to the action of the weighted arm 30 which was lifted by the movement of the sector 27 and the block 28 occurring when the parts were operated to cause the lighting of the yellow lamp Y, as previously described.

As indicated hereinbefore, not only is it necessary for the proper operation of railway block signaling systems to change from a stop indication to a caution indication, but also to change from a cantion indication to a proceed indication without giving the stop indication, even temporarily. 'According to the embodiment of the invention illustrated,

this latter change from a caution indication to a proceed indication is obtained by energizing the motor so as to rotate the pinion in the direction opposite to that indicated by the arrow 0. At this time the contact fingers 707 2 are contracted and the inertia member 47 is turned against the stop '52, as previously described; and when turning torque is applied to the pinion 26 in the direction opposite to that indicated by the arrow 0, the sector 27 is rocked in the direction opposite tothat indicated by the arrow b, and each contact member carried-by the block 35 is moved from its la'wer position toits upper position or from one extreme positlon tothe other extreme position. By referring to Fig. 2 it will be seen that, in moving from its lower position to its upper posi- 'tion, the finger 88 breaks contact with the post 89, thereby interrupting the circuit for the yellow lamp Y, and makes contact with post. 98, thereby establishing another. circuit for lighting the green lamp G.

When the contact carrying block 35 is moved continuously from one extreme position to the other, the tendency of the contact fingers 7072 acted upon by the compression s rings 46 'is to separate and assume their intermediate position as shown in Fig. 2; but inorder that these contact fingers may move apart from their contracted position, it is necessary for the inertia member 47 to turn about its axis and i in accordance with the. well known principle of inertia, it is apparent that a little time is required to set'the inertia member in motion and move it from its operated. sition to the position shown in Fig. 2. be weighted ends 4:7 and 47 of the inertia member 47 are so proportioned that the time required for the inertia of said inertia member 47v to be overcome by the action of the springs 461s greater than the time required for the motor to move the contact carrying block 35 from one extreme position to the other extreme position, so that the contact fingers 7072 will not spread apart far enough to touch the contact posts 69-73 and permit the circuit that is formed in the intermediate position to be closed as the motor drives .the contact carrying block 35 continuously ast its intermediate position. After the mger 70 comes in contact with contact osts 69, the continued upward movement-o the arm 48 causes the inertia member 47 to be turned around its axis back to its former position, and the contact fingers 70--72 will again be contracted.

A further and more detailed description that is, the red lamp R at signal 6 giving the sto indication is lighted, the yellow lamp Y at signal 5 giving the caution mdication is lighted, and the green lamp G at the signal 4 giving the proceed Indication is lighted-' Referring morein detail to the position of the. parts andcontrolling circuits established when a train 7 occupies the block D, the presence [of the wheels and\axles of this tram onthe track rails 1 and 2 of the block D shunts the track winding 17 2 of the track relay 16, thereby causing the contact fingersof this relay to assume their biased sition and establishing a circuit for lighting the red lamp R at the signal 6 which may (lie traced as follows and which is herein ca e Circuit Number One.

Commencing at one terminal of the second-' ary 21 of the transformer 13, wires 67 and 68, contact point 69 one contact finger 70 of the group F of the contact fingers on the track relay 16, Wire 71 the other contact finger 72 of said group of contact fin ers, contact point 73 wire 74?, red lamp 1 at signal '6, and wires 7 5 76 7 7 and 25 back to middle tap of the secondary 21 of the transformer 13.

a When the train 7 occupies the block D and the track relay 16 is deenergized, as shown in Fig 1, circuit for energizing the track winding. 17 of the track relay 15 controlling the signal 5 at the entrance to the block C may be traced as follows and is herein called Circuit Number Two.

Commencing at the middle tap of the secondary 21 of the transformer 13, wires 25,

24 and 78 track rail 1 of the block C, wire 18, track winding 17 of the track relay 15, wire 19, track rail 2 of the block C, wires 79 and 80, contact point 81 one contact finger 82 of the group 2 of the contact fingers of the track relay 16 in its deenergized condition, wire 83*, the other contact finger 84 of the said group E of contact fingers, contact point 85 and wire 86 back to another tap of the secondar'y21 of the transformer 13.

It is well known to those skilled in the art of railway signaling that in alternating current relays of two-element type illustrated, the rotor of the-relay motor may be caused to rotate in one direction or the other, depending upon the relative direction of the How of current in the track and local windings of the relay. As previously stated, the local winding 20* of the track relay 15 is permanently connected to the secondary 21 of the transformer 12, and consequently at every instant the relative direction of theflow of current in the track winding 20 of the relay 15 and in the secondary of the transformer 12 is the same; but since the primaries of the transformer 11, 12 and 13 are connected to the same line wires 8 and 9, the relative direction of the flow of current in the secondaries of these transformers is the same at every. instant, and it is only necessa to change the connections between the trac winding 1720f the track relay 15 with the secondary of the transformer 13 in order to change the direction of rotation of the rotor of said track relay The local winding 20 and the track winding 17 of the track relay 15 are so arranged that when circuit Number Two is established, the con tact fingers of saidrelay are moved to the right as viewed in Fig. 1; and in this position of the contact finger 88 of said relay there is established a circuit for'the yellow lamp Y at signal 5 which may be traced as follows and is herein called Circuit. umber T h'ree.

Commencing at one terminal of the secondary 21 of the transformer 12, wires 67 and 87 contact finger 88 moved to itsrighthand extreme position as shown on the drawing, contact point 89, wire 90 yellow lamp Y at the signal 5, and wires 91 76 ,77 and 25 back to the middle tap of the secondary 21 of the transformer 12.

From the foregoing it can be seen that when a train occupies the block D, as shown in Fig. 1 of the drawings, that it is not only guarded by a red light at the signal 6 at the entrance to the block D, but it is also guarded by a yellow light at the signal 5' at the entrance to the block C next in the rear of theblockD. a c

When the track relay 15 is energized so that itscontactfingers are moved to their righthand extreme position, as viewed in the drawing, the circuit which controls the track wind1ng-17of the track'relay 14 for controlling'the signal 4 at the entrance to block B, that is," the block second in the rear of the block D which the train 7 occu: ies, is established and may be traced as fol i o'ws and is herein called Circuit Number Four: I

Commencing-at the middle tap of the secondary 21 of the transformer 12, wires 25 24: and 7 8 track rail :1 of the block B, wire 18, track winding 17 of the track relay 14, wire 19, track rail 2 of the block B, wires 79 and 96 contact-finger 95 0f the track relay 15 moved to its righthand extreme position, contact point 94 and wires 93 and of the relay 14 are in the lefthand extreme position, as shown in'Fi 1, there is estab lished a circuit which lig ts the green lamp G at the signal 4, to indicate proceed, or t that the two blocks next in advance are. not

occupied. This circuit may be traced ,as

follows and is herein called Orcuit Number Five. Commencing at one terminal of the sec ondary 21 of the transformer 11, wires 67 and 87, contact finger 88 of the track relay 14in its lefthand extreme position,'contactl point 98, wire 99, green lamp G at the signal 4, wires 100, 77 and 25 back to the middle tap of the secondary 21 of the transformer 11.

It will thus be block B nor the block G is occupied by a train the signal 4 for the block B will dis play a green light denoting proceed, and the operator of an approaching train upon seein said green light may proceed into the b ock B knowing that two blocks ahead, are unoccupied.

Assuming that the train 7 now moves out of the block D and into the next block in advance of the block D which is not shown but which ma be conveniently referred to .as the block The track winding 17 of the track relay 16 is now no longer shunted seen that when neither the and becomes energized"; but due to the pres ence of the train in the block E, it will be readily understood by those skilled in the art of automatic'block signalin for railways, that the direction of the ow of current throu h the track winding 17 relatively to that t rough the local winding 20 is such asto cause the contact fingers of the track relay 16 to move to the righthand extreme position in exactly the same manner as the train 7 formerly assumed to be in the block D caused the contact fingers of the track r'elay 15 to move to the righthand position, as hereinbefore described. As a result of this movement of the contact fingers of the relay 16; the circuit Number One for lighting the red light R at the si a1 6 is broken and a circuit for lightin t e yellow lamp Y at said si al is establisfiied, which may be traced as f0 lowsand which is herein called Czrcuit Numta Sim.

Commencing at one terminal of the secondary 21 of the transformer 13, wires 67 and. 87', contact finger 88 of the track re lay 16 in its extreme righthand position, contact point 89, wire 90 ,,yellow lamp Y, and wires 91, 7 6 77 2 and 25 back to the middle tap of the secondary 21 of the transformer 13. I t

Also, when the contact fingers of the track relay 16 are moved to their extreme righthand position as hereinabove described, the circuit Number, Two for supplying current of. one polarity to the. track winding 17 of the track relay 15 is broken, and there is established another circuit which energizes the track winding17 with current of cuit may be traced as follows and is herein called Circuit Number Seven.

Commencing at the middle tap of the secondary 21 of the transformer 13; wires 25, 24 and 7 8 ,.track rail 1 of the block C, wire 18 track winding 17 of the track relay 15,

' wire 19 track rail 2 of the block C, wires 79 and 96 contact finger 95 of the track relay- 16 in its extreme righthand position,

contact point 94 and wires 93 and 92 back to 1 another tap of the secondary 21 of the transformer 13.

When the contact fingers of the track relay 15 are moved :lirom the extreme righthand position to the extreme lefthand position, there is established a circuit which lights the green lamp G at the signal 5, and which may 1 be traced as follows and is herein called Circuit Number E fight.

Commencing at one terminal of the secondary 21 01: the transformer 12, wires 67 and 87, contact finger 88 of the relay 15 in its extreme lefthand osition, contact point 98, wire 99 green amp G, and wires 100 77 and 25 back to the middle tap of the secondary 21 of the transformer 12.

'During the shifting of the contact fingers of the track relay 15 from the righthandposition, as shown in Fig. 1, to the opposite lefthand position, the inertia member 47 associated with the pairs of contact fingers E and F prevent these pairsof contact fingers from closing the respective circuits controlled thereb for the reason explained hereinbefore, so that, during the changefrom a caution indication at the signal 5 to a proceed indication, there is no flashing of the red lamp to give the objectionable stop indication. Also, the pairs of contact fingers E of the track relay 15 do not'close the circuit, analogous to circuit Number Two, for'cha'nging the polarity of the current in the track winding 17 of the track relay 14, and as soon as the contact finger 94 of the track relay 15 assumes its lefthand position a circuit for the track winding 17 of the track relay 14,

which is substantially the same as circuit Number Four is established, thereby maintaining the track relay 14 in the same energized condition shown in Fig. 1.

From the foregoing it can be seen that this invention provides an automatic block signaling system inwhich light signals, or other signalswhich' give'their indications by the closing of circuits, can belused without any obj ectionableor false indications being given,

and in'which the polarized track circuit control can be used without requiring any reiays or other devices in addition to track reays. 7

Although I have particularly described the construction of one physical embodiment of my invention, and explained the operation and principle thereof; nevertheless, I desire to have it understood that the form selected is merely illustrative, but does not exhaust the possible physical embodiments of the idea of means underlying my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is: p

1. In a signaling system for railways, in combination: a stretch of track divided into track circuit blocks; a signal for guarding the entrance to each block; a polarized track relay associated with each block and having a biased position and two operated positions; circuits for controlling each signal selectively controlled by the corresponding track relay; and means governed by each track relay for controlling the polarity of the track circuit of the block next in the rear of the block corresponding to that track relay; each track relay including means for preventing the closing of the signal controlling circuit controlled in the biased po-' sition of said track relay when said track relay is operated continuously from either operated position to the other operated position.

2. In a block signaling system for railways, in combination: a plurality of track circuit blocks; a polarized track relay associated with each block; a light signal guarding the entrance to each block; and a circuit for the stop indication of each si nal including contacts of the correspon ing track relay which tend to close when that relay is deiinergized, each track relay including means associated with said contacts for preventing their closure when the energizing current of the relay is changed immediately from one polarity to the other.

3. In a signaling system for railways, in combination: a stretch of track divided into track circuit blocks; a light signal for guarding the entrance to each block and capable of assuming three different aspects; and a polarized track relay associated with each block and controlling the aspects of the corresponding signal; said track relay comprising means for preventing its contacts closing to cause the signal controlled thereby from tending to assume its stop aspect while the energizing current of that track relay is being changed immediately from one polarity to the opposite clarity.

4. In a signaling system or railways, in combination: a stretch of track divided into track circuit blocks; a light signal for guarding the entrance to each block and capable of assuming three aspects; circuits for controlling the aspects of each signal;

a polarized track relay associated with each block; each track relay including circuit controlling means for selectively opening and closing said circuits.

5. In a signaling system for railways, in combination: a stretch oftrack divided into blocks; a polarized track relay associated v with each block; a signal for guarding the entrance to each block and governed by the corresponding track relay; a source of current for each block; circuit controlling ineans operated by each track relay for controlling the connection between the track rails ofuthe next block in the rear and its source of current; said circuit controlling means being ada ted to establish such a connection of one polarity when said track relay is deenergized and a connection of the opposite polarity when said track relay is energized by current of either polarity; and means for controlling each of said circuit controlling meansto prevent the first mentioned connection 'being established when the energization of the corresponding track relay is changed immediately from one polarity to the opposite polarity. V

6. In a block'signaling system for railways, in combination: a stretch of track divided into track circuit blocks; a signal for guarding the entrance to each block; a circuit for controlling the stop aspect of each signal; a polarized relay associated with each signal and having contact fingers which are adapted to spread apart when the relay is denergized to establish the continuity of the corresponding circuit; and means for temporarily delaying the change of said contact fingers upon denergization of the relay.

7. In a block signaling system for rail- Ways, in combination: a stretch of track divided into track circuit blocks; a signal for guarding the entrance to each block; a polarized track relay associated with each block and having contacts closed when the relay is denergized; a circuit forcontrolling the stop aspect of each signal including said contacts of the corresponding track relay; and means associated with said contacts for temporarily delaying their closing upon deenergization of the relay.

8. Ina block signaling system for railways, in combination: a stretch of track divided into track circuit blocks; a signal guarding the entrance to each block; a polarized track relay associated with each block and governing the aspects of the corresponding signal; circuit controlling means A operated by each relay when deenergized for reversing the polarity of the track circuit next in the rear; and means for temporarily delaying the operation of said circuit controlling means upon denergization of the corresponding track relay.

WILLIAM H. WORKMAN. 

